The present disclosure generally relates to ultrasound imaging systems and medical devices and more particularly to the use of such systems and devices for needle procedures such as biopsies, nerve blocks, and vascular access.
Ultrasound is the most common medical imaging modality after X-ray imaging. The benefits of ultrasound are clear: it is safe, relatively affordable, and fast. Given these benefits, it is no surprise that ultrasound usage is increasing.
Doctors commonly use ultrasound to guide needle placement in patients. For example, where there is a suspicion of breast cancer, a practitioner will use ultrasound on a patient to visualize a suspicious lesion and subsequently guide a needle to acquire a tissue sample from that lesion for testing. Such needle procedures are typically difficult for a number of reasons. First, ultrasound image-guided procedures require expert hand-eye coordination. Second, even under optimal imaging conditions, ultrasound can be difficult for a number of reasons. The resulting ultrasound image does not accurately depict the exact location of tools, such as needles or catheters, due to the specular reflector nature of the materials of the tools. Furthermore, ultrasound images can be colorless, speckled, and difficult to interpret. These factors add to time and complexity of ultrasound-guided procedures while decreasing precision and confidence.
Myriad approaches try to address these and other issues. For example, U.S. Pat. No. 5,329,927 describes a vibrating mechanism coupled to a cannula or needle for Doppler enhanced visualization. Such an arrangement unfortunately requires additional workflow steps including having to sterilize and then attach the vibrating mechanism. Furthermore, smaller ultrasound units may not have Doppler capability required for functionality.
Several needle manufacturers have used echogenic or texturing methods to enhance needle visibility such as that described in U.S. Patent Application Publication 2012/0059247. The texture is generally a dimpling or scoring of a typically smooth surface to reduce the specular reflector properties. Results show that these textured needles only provide slight benefit in ideal conditions.
Another approach to try to effect accurate needle guidance is to restrict the motion of the needle within the ultrasound imaging plane. For example, U.S. Pat. No. 6,485,426 describes a frame that clips onto the ultrasound imaging probe and biopsy needle to direct the needle. Such an arrangement unfortunately also adds steps to workflow and sterilization. Furthermore, the arrangement severely limits the important aspect of range of motion for needle manipulation.
Yet another attempt to improve ultrasound guidance is by way of an electromagnetic (“EM”) position sensing system to detect the needle tip in relation to the ultrasound imaging probe and then annotate the ultrasound image accordingly. Such a system is made by Ultrasonix. However, this system is a proprietary one that requires specific compatibility between the needles and the imaging system and therefore limits the range of procedures. Furthermore EM sensing is costly, requires a calibration step, and is prone to registration error with the ultrasound image.
Ultrasonix also released a spatial compounding feature for enhanced needle visualization. This feature relies on enhancing straight line features in the image, and therefore requires the needle to be in the imaging plane to be useful.
A further attempt to improve ultrasound guidance involves a stylet having an ultrasound transducer associated therewith, wherein the stylet is carried within a hollow biopsy needle. Such an arrangement is described in U.S. Pat. Nos. 5,158,088; 4,407,294; and 4,249,539. In particular, the stylet is a wired, non-disposable device that signals acoustically and/or electronically between the tool in question and the ultrasound imaging device for ultrasound image enhancement. Unfortunately, this attempt also introduces a number of additional steps into the clinical workflow. For example, using the stylet requires an additional step of placing the stylet into the hollow needle. Moreover, as the stylet is non-disposable, it must be sterilized before each use. In addition, because the stylet must be used along with other tools, only certain types of tools are compatible with the system.
Accordingly, an ultrasound device for needle procedures that is simple to use, wireless, disposable, accurate, and compatible with pre-existing ultrasonic diagnostic imaging systems and devices is therefore desired.